#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 5e5 + 5;
int n;
array<bool, MAX_N> a;
struct Node {
int l_open, l_close;
int r_open, r_close;
int pairs;
} st[4 * MAX_N];
Node merge(Node x, Node y) {
int l_del = min(x.l_open, y.l_close);
x.l_open -= l_del, y.l_close -= l_del;
int r_del = min(x.r_open, y.r_close);
x.r_open -= r_del, y.r_close -= r_del;
x.pairs = min(x.pairs, x.r_open);
y.pairs = min(y.pairs, y.l_close);
Node ans = {x.l_open + y.l_open, x.l_close + y.l_close,
x.r_open + y.r_open, x.r_close + y.r_close,
x.pairs + y.pairs};
if (x.r_open > x.pairs && y.l_close > y.pairs)
ans.pairs += min(x.r_open - x.pairs, y.l_close - y.pairs);
return ans;
}
void build(int u = 1, int lo = 1, int hi = n) {
if (lo == hi) {
if (a[lo] == 1) st[u].l_open++, st[u].r_close++;
else st[u].l_close++, st[u].r_open++, st[u].pairs++;
return;
}
int mid = (lo + hi) / 2;
build(2 * u, lo, mid), build(2 * u + 1, mid + 1, hi);
st[u] = merge(st[2 * u], st[2 * u + 1]);
}
Node query(int l, int r, int u = 1, int lo = 1, int hi = n) {
if (r < lo || hi < l) return Node();
if (l <= lo && hi <= r) return st[u];
int mid = (lo + hi) / 2;
return merge(query(l, r, 2 * u, lo, mid), query(l, r, 2 * u + 1, mid + 1, hi));
}
int main() {
// freopen("elec.in", "r", stdin);
cin >> n;
for (int i = 1; i <= n; i++) {
char ch; cin >> ch;
a[i] = (ch == 'C');
}
build();
int q; cin >> q;
for (int i = 1; i <= q; i++) {
int l, r; cin >> l >> r;
Node resp = query(l, r);
int ans = resp.l_close + resp.r_open - resp.pairs;
cout << ans << '\n';
}
}
